A number of economically important plants are significantly sensitive to commercially utilized herbicides. These herbicides include herbicides which are or, absent adverse effects toward desired plant species, could be used to control weeds among a particular desireable plant stand; or herbicides which are known to damage a particular plant species, but come into contact with that plant species for example in run-off from an adjacent, different, non-sensitive plant stand which has been treated with the particular herbicide. At least one example of this latter problem is the damage done to alfalfa crops planted in proximity to corn crops when certain herbicides, commonly used to treat corn fields, accidently enter the alfalfa field.